More likely a function of how application (program) software
was written. One reason for so much instability in DOS and
Win9x based OSes was that programs accessed hardware
directly. Win NT based OSes channel all hardware access via
OS control. If your application software was doing very
unstandard port access, then all NT based OSes will create
problems.
But to better answer your question, best to start by
describing the application details of serial port you are
using. The only really acceptable use of a serial port is
terminal equipment (ie computer) connected to communication
equipment (ie. modem). Most other implementations are
perversions of the RS-232 standard.
And so we start with which serial port wires are being
used. Besides transmit, receive and signal ground, is your
port using DTR, DSR, etc? IOW which pins interconnect
computer to industrial controller and which are jumpered back
to computer or industrial equipment serial port? Using flow
control - and is it hardware or software flow control?
Welcome to the non-standard Standard called RS-232.
